linux-kernel - Re: [PATCH] arm64: disable kasan when accessing frame->fp in unwind

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Date:	Mon, 8 Feb 2016 11:51:01 +0300
From:	Andrey Ryabinin <aryabinin@...tuozzo.com>
To:	Yang Shi <yang.shi@...aro.org>, <Will.Deacon@....com>,
	<Catalin.Marinas@....com>
CC:	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH] arm64: disable kasan when accessing frame->fp in
 unwind_frame



On 02/06/2016 02:04 AM, Yang Shi wrote:
>  
>  #include <asm/irq.h>
>  #include <asm/stacktrace.h>
> @@ -64,7 +65,9 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
>  		return -EINVAL;
>  
>  	frame->sp = fp + 0x10;
> +	kasan_disable_current();
>  	frame->fp = *(unsigned long *)(fp);

It would be better to use READ_ONCE_NOCHECK() here.
See f7d27c35ddff7 ("x86/mm, kasan: Silence KASAN warnings in get_wchan()") which solves the same problem for x86.

> +	kasan_enable_current();
>  	frame->pc = *(unsigned long *)(fp + 8);

Why you left frame->pc out of scope? This line could trigger kasan as well.

>  
>  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>